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ichudov

I bought this truck at auction. It has Cummins ISX 385 engine "7CEX".

I brought it home and did not notice anything, unloaded from my lowboy and took it for a quick ride. After a few minutes I noticed that it emits a lot of white smoke. The smoke seemed to smell of coolant. I also notice that though the smoke was copious, it disappeared momentarily when I would push the gas pedal to rev up the engine. Video:

https://youtu.be/5vtMqeNajNg

A day later, I went to work to look at it closely, added more coolant and started again. To my surprise, the exhaust on the second day did NOT smell of coolant, at least when the engine was cold. Here's the second day video:

https://youtu.be/_roBlfNtnIc

I shut it off without much investigation but I would like to properly examine it and understand why it may be smoking and giving these symptoms.

I would GREATLY appreciate your suggestions.

hhow55

Likely blown head gasket
Drop the oil pan
Pressure up coolant system to 20 lbs and see if coolant runs down the inside of liners

ichudov

Thanks! I think that first, I will pressurize the coolant system and see how it holds pressure?

Chamberpains

You won't be just pressurizing the coolant to see if it will hold pressure. Your going to need to drain the oil, remove the oil pan, then pressurize the coolant system up to 20 PSI. Let it sit over night and check up around each cylinder to find coolant running down. Then you will also want to bar the engine over to see if any of the cylinders start leaking or gurgling coolant.

Rawze

you might also want to check the EGR cooler, doser injector, and other things for wetness as well.

ichudov

Rawze, thanks a lot. I will try to open up those things to look for wetness.

Any idea if the fact that it does not emit coolant smoke all the time, is suggestive of any specific hypothesis. I noticed that just after starting cold, it did not seem to smoke white quite as bad. But after I ran it the first day for maybe 20 minutes, and drove it, it smoked white a lot.

The coolant overflow tank also does not bubble.

Also, at least at idle, there is not that much blowby.

Waterloo

Check the EGR cooler first, pressurize the coolant system and pull the hose off the back side of the EGR cooler, put a saucer or something similar to catch any leaking coolant while the truck sits overnight under pressure, 20 psi. If it is bad, you will find coolant, and at least have a place to start.

Look for leaks in general too. It will be a good idea to drop the DPF/DOC cans too to inspect, they are more than likely toast if coolant is coming out the exhaust, no matter its origin.

I would start at the EGR cooler and then go from there. No bubbles or pressure build up in the coolant tank is a good sign.

I would also head up to NAPA, if they are open in your area, and get one of their "Block Test Kits", they run around $50, I have used them in the past and they work. Just make sure you have the motor nice and hot before running the test.

Rawze

if your not loosing any coolant, it could simply be the regeneration system not getting hot enough, then burning off all at once. - You did however specifically state it smelled like coolant, so it is not a bad idea to drop the pan and at least check it all out, not knowing the overall state of it.

ichudov

I will check hopefully tomorrow if I am losing coolant and open up a few things. Thanks Mr Rawze!